Preparation of trimeric ruthenium tetracarbonyl



Unite 3,387,332 PREPARATEQN F TRIMEREC RUTHENIUM TETRACARBONYL Piero Pine, Fisa, and Guiseppe Brace, S. Frediano a Settino, Pisa, Italy, assignors to Lonza Ltd, Basel, Switzerland No Drawing. Continuation-impart of application Ser. No. 341,132, Jan. 29, 1964 This application July 29, 1965, Ser. No. 475,340 iaims priority, application Switzerland, Feb. 1, 1963,

1,292/63; Aug. 5, 1964, 10,200/64 3 Claims. (Cl. 23-203) ABSTRACT (ME THE DISCLOSURE The invention relates to the preparation of trimeric ruthenium tetracarbonyl which is useful as catalyst in Reppe syntheses, hydroforming and carbonylating processes.

Three different ruthenium carbonyl compounds have been described in the literature, namely an unstable colorless liquid having the formula Ru(CO) a solid compound crystallizing as orange crystals from benzene, whose composition was originally given by M. Manchot and W. I. Manchot (Z. anorg. allg. Chemie 226 (1936), p. 385) as ruthenium enneacarbonyl Ru (CO) and a green crystallized compound to which the formula [Ru(CO) was attributed. Recently, the stable form of the compound considered by W. Manchot to be Ru (CO) was determined by E. Corey and L. Dahl (J. Am. Chem. Soc., 83 (1961), p. 2203) to be [Ru(CO) The structure of the green crystallized compound has not yet been confirmed.

Heretofore, the trimeric ruthenium tetracarbonyl had been prepared either from metallic ruthenium sponge, or from inorganic ruthenium salts such as RuS or halides, which were reacted with carbon monoxide under high pressure. In all said reactions, there is first formed rutheniumpentacorbonyl, which is a volatile liquid of low stability and must be isolated; such recovery procedure involves inconvenient manipulations and results in a low yield of trimeric ruthenium tetracarbonyl in the subsequent synthesis.

When reacting CO with an organic ruthenium salt, a direct formation of trimeric ruthenium tetracarbonyl in a single step process was never observed.

It is a principal object of the invention to provide a process for the preparation of trimeric ruthenium tetracarbonyl which avoids the drawbacks presented by the intermediate formation of ruthenium pentacarbonyl.

Other objects and advantages Will be apparent on consideration of the specification and claims.

According to the invention, trimeric ruthenium tetra carbonyl is prepared by reacting an organic ruthenium salt with carbon monoxide and hydrogen in the presence of an organic liquid which under the reaction conditions is a solvent for the ruthenium salt, CO and H at a temperature of 100 to 250 C., preferably 140 to 160 C., and at a pressure of J50 to 350 atm., preferably 150 to 200 atm.

States Patent 0 Patented June 11, 1968 Suitable organic liquids which are solvents for the reactants under the reaction conditions are, for instance, benzene and similar aromatic hydrocarbons. If the solvent contains an active H atom, the addition of gaseous hydrogen can be omitted. Suitable such solvents are methyl ketones, e.g. acetone, and aliphatic monohydric alcohols having 1 to 4 carbon atoms, such as methanol, propanol, isopropanol, n-butanol, and others.

The reaction can be carried out even with water as solvent though the formation of decomposition and byproducts will result in lower yields.

Suitable ruthenium compounds are, for instance, the basic ruthenium salts of carboxylic acids, such as basic ruthenium benzoate, basic ruthenium succinate, basic ruthenium acetate, and the enol compound ruthenium acetylacetonate, which is our preferred starting material.

The reaction pressure may be adjusted by forcing carbon monoxide or a mixture of carbon monoxide and hydrogen in a molar ratio in the range of 5:1 to 1:1, preferably 3 :1 to 2.5: 1, into the reactor. Any type of pressureresistant vessel can be used; we prefer to use reactors in which the reaction medium can be shaken, agitated or vibrated.

After termination of the reaction, the formed trimeric ruthenium tetracarbonyl is present essentially in the form of orange-red crystalline platelets in the solvent. The mother liquor can be processed in various ways. It may be distilled 01f, after separation from the trimeric ruthenium carbonyl, in vacuo whereupon additional trimeric ruthenium tetracarbonyl may be recovered by dissolving it out of the residue, e.g. with acetone, and recrystallization. In another modification, the mother liquor is, prior to or after separation from the trimeric ruthenium tetracarbonyl, left standing for several hours, for instance 3 to 24 hours, in an inert gas atmosphere, for instance carbon monoxide or nitrogen. Such treatment produces an increase of the yield of the trimeric ruthenium tetracarbonyl. It is of course of advantage to recover first the crystalline trimeric ruthenium tetracarbonyl formed in the reaction before the mother liquor is subjected to the after-treatment in an inert gas atmosphere.

Finally, the mother liquor may, after recovery of the trimeric ruthenium tetracarbonyl, be processed for the recovery of metallic ruthenium by evaporating the solvent, calcining the residue, and treating it with hydrogen.

The process of the invention does not only produce high yields but offers the further advantage of a simple recovery of the trimeric ruthenium tetracarbonyl because substantially no insoluble by-products are obtained.

In order to illustrate the invention, the following specific examples are given. It will be understood that variations from the particular compounds and proportions can be made without departing from the invention.

Example 1 3.2 g. of ruthenium acetylacetonate were placed in a shaking autoclave of stainless steel having a capacity of cm. The air was swept out, and 30 cm. of methanol were introduced. Subsequently, a mixture of carbon monoxide and hydrogen in a molar ratio of 3 :1 was forced into the autoclave until a pressure of 155 atm. Was reached, and the autoclave was heated at C. with shaking. The autoclave was maintained at 150 C. for about 4 hours, whereby a slight pressure drop was observed.

After cooling, the autoclave was opened and the discharged gas was passed through a trap cooled with liquid air to crystallize any volatile Ru(CO) which might have been formed. No such Ru(CO) could be detected.

After emptying the autoclave, 1.17 g. of [Ru(CO) could be separated as orange-red platelets from the methanol. Additional 0.133 g. of [Ru(CO) were obtained by processing the methanolic mother liquor. The total '3. a of 1.303 g. of [Ru(CO) corresponds to a yield of liquor, additional 0.24 g. of [Ru(CO) could be re- 76.3%,calculated on the ruthenium acetylacetonate. covered, corresponding to a total yield of 0.65 g. of Ru .e. 9 .3 calc te o. t he l- Example 2 (C 1 0 ula d a rut mum acety acetonate. The same apparatus as used in Example 1 was filled 5 The following table gives the results of additional with 1.06 g. of ruthenium acetylacetonate and 75 cm. examples.

After-treatment Yield Example Ruthenium compound Solvent Pressure Temp, Time,

N o. of 00 atm. 0. hours Inert gas Time, G. Percent liOUIS 6. 2g.ruacetylacetonate 151 152 5 Nitrogen. 0.74 (10.2 7. --.do 150 150 0.22 20. o 8. .do 142 160 5 0. 53 49. 5 9. 2 g. basic rusuccinate... 150 160 9 O. 64 6-1 10... 9 g. ruacetylacetonate. 152 160 7 0.18 1 42 11 do 27 0111. metnylethylketoue. 149 160 5 .do 0177 49.4

1 In example 10, there were recovered 1.2 g. of unreacted ruthenium acctyl acetonate, and in Example 11 1.37 g. In both examples, ti. yields were calculated on reacted ruthenium aeetyl acetonate.

of benzene. The reaction was carried out at 150 atmos- Formation of trimeric tetracarbonyls of other metals pheres under otherwise exactly the same conditions as of the VIIlth group of the periodic system by the reacset forth in Example 1. 9 tion of CO and H with organic salts of such metals, for The formed trimeric ruthenium tetracanbonyl was cominstance with the iron salt of acetylacetonate, could not pletely dissolved in the benzene and was recovered by be observed. distilling oif the solvent in vacuo. There were obtained It is to be understood that the term compound con- 0.35 g. of [Ru(CO) corresponding to a yield of taming a hydrogen atom which is reactive under the reac- 51.5%. tion conditions is intended to cover compounds subject Analysis.-Calcd: Ru 47.65%. Found 47.09%. to the Zerewitinoff determination (Merck, 7th ed., page E 1480), or compounds which may be subjected to the xample 3 Zerewitinoff determination under the reaction conditions,

1.21 g. of basic r th nium a et or compounds which under reaction conditions may form after displacement of the air, 7 cm. of methanol were @[har compounds hi h may b bj d to h Z introduced into the autoclave used for the preceding eX- witinoif determination.

amples. CO and H in a molar ratio of 3:1 were forced W l i into the autoclave until the pressure was 165 atm., and 1. A process for the direct preparation of an orangethfi tfimperature was falsed 'Wlth g- Dllrred trimeric ruthenium tetracarbonyl from organic ing the reaction, the pressure dropped somewhat. After 3 hours, the reaction was terminating and the autoclave ruthenium compounds comprising reacting in the abwas Opened. The discharged gas was passed through a from a group consisting of basic ruthenium salts of trap cooled with liquid air whereby no Ru(CO) could carboxylic acids and ruthenium acetylacetonate with be dctfiCied. 0.05 g. Of trimeric ruthenium tetracarbonyl carbon monoxide at a temperature of 140 to 160 C. and could be recovered at the bottom of the autoclave in form 40 at a pressure in the approximate range of 150 to 200 ("Egg-fed P The methanolic mother liquor, atmospheres in the presence of a Compound selected from after distillation of the methanol and recrystallization of the group consisting of methyl ketones and aliphatic the residue from acetone, yielded (U30 2' 0f )-ilamonohydric saturated alcohols having 1 to 4 carbon Calculated on the basic ruthenium acetate, the yield was t id compound containing a reactive hydrogen 23.4%. atom and being a solvent for the reactants under the Example 4 reaction conditions, said carbon monoxide being substantially the sole gaseous reactant, and separating the obtained trimeric ruthenium tetracarbonyl from the reaction medium.

2. The process as claimed in claim 1 comprising carry- 59 ing out the process in an autoclave, releasing the autoclave pressure after termination of the reaction, and maintaining after said pressure release the solution of the trimeric ruthenium tetracarbonyl during 3 to 24 hours under an inert gas atmosphere, thereby increasing the yield of crystalline ruthenium tetracarbonyl.

3. The process as claimed in claim 1 wherein said compound is a monohydric saturated alcohol.

The shaking autoclave used in the preceding examples was charged with 3.83 g. of ruthenium acetylacetonate and, after removal of the air, with 50 cm. of methanol. Then CO was forced into the autoclave until a pressure of 153 atm. was reached, and the autoclave was heated up to 150 C. with shaking. While the pressure dropped slightly, the autoclave was kept at said temperature for about 9 hours. After cooling, the autoclave was opened and discharged.

1.02 g. of {Ru(CO) were recovered from the motor liquor as orange-red platelets. The methanolic mother liquor was left standing in a nitrogen atmosphere for additional 12 hours. After removal of the methanol by distillation in vacuo, additional 0.76 'g. of [Ru(CO) References Cm} Obtaimd 60 UNITED STATES PATENTS The yield, calculated on ruthenium acetylacetonate, 2,473,993 6/1949 Gresham et al. 23-203 was 86.8%. 2,477,554 7/1949 McKeever 23-203 Example 5 2,717,201 9/1955 Passino 23-203 X 2,865,716 12/1958 Hasek 23-203 An autoclave as described in Example 1 was charged 05 ith 1.35 g. of ruthenium acetylacetonate and, after reclasson et moval of the air, with 25 cm. of isopropanol. By means 3:236:597 5 5 E S i ii' 3:

of CO, the pressure was adjusted to 150 atm., and the temperature was raised with shaking, to 154 C. At said FOREIGN PATENTS temperature, the autoclave was shaken for 3 more hours, 70 6 r whereby the pressure decreased slightly. After cooling 8 0645 2/1961 Great Bntam' and venting, the motor liquor was left standing additional MILTON WEISSMAN, Primary Examiner. 10 hours under a nitrogen atmosphere. Subsequently, 0.41

g. of [Ru(CO) could be separated from the motor OSCAR VERTIZ Examiner liquor in form of platelets. After processing the mother B. H. LEVENSON, Assistant Examiner. 

